It may be a bit awkward at Thanksgiving dinner this year for some high-profile Republican politicians and their families as the party grapples with shifts in American attitudes toward gay marriage.

Last month an organizer with Human Rights Campaign, a group that advocates for LGBT rights, asked Cindy McCain to sign a postcard petitioning Arizona’s Republican senators—including McCain’s husband—to fight discrimination against LGBT Americans.

She signed the card. It apparently arrived at the senator's office, because John McCain’s spokesman offered this curt public response via e-mail to The Washington Post: "Senator McCain enjoys and appreciates having discussions on the important issues of the day with all the members of his family, and he respects their views." Senator McCain opposed gay marriage when he ran for president in 2008.

This comes just a few months after McCain's daughter Meghan, a young Republican who publicly supports gay marriage, presented her mother with a Trevor Hero Award for supporting gay rights.

Wonder if that will come up as relatives pass the gravy.

Things will probably be even more awkward for Cheney family members, should they attempt to celebrate this holiday of togetherness together—unlikely though it may seem after Liz Cheney’s vocal denouncing of gay marriage started a public feud between Liz, her sister Mary, and Mary’s wife, Heather Poe.

The question of family has loomed large for the Republican Party for decades. But as a growing number of Americans embrace a definition of family that includes same-sex couples, the once obvious choice to oppose gay marriage has become a bit murkier for Republican political candidates.

The Republican Party is very much aware of the change in national sentiment on this issue, "particularly among young voters," says Natalie Davis, professor of political science at Birmingham-Southern College.

And younger Republican candidates with big ambitions are in the most awkward position.

It depends "if they are trying to position themselves for a future presidential run in five years as opposed to in 20 years," says Melody Crowder-Meyer, assistant professor of politics at Sewanee: The University of the South. "If you're trying to take action sometime sooner, you don't want to cut off a certain segment of voters."

Regardless of what's happening on the national stage, "there are a great many House districts in which the way candidates will win is to win over strong partisans who are socially conservative," says Crowder-Meyer. "Think of the Southern Democrats in the 1960s. The national party was becoming very liberal on racial issues," but Southern Democrats won races for years by sticking with their white constituents' backward views on race.

But candidates are noticing that even in states where marriage equality became law by a whisper-thin margin, opposition soon softened.

In Maine, 87 percent of voters surveyed by Public Policy Polling one year after gay marriage became legal said the legalization had no impact or had a positive impact on their lives. The measure had been approved by six points at the polls, but those surveyed a year later came to support it by a 17-point margin (54 percent in support, 37 percent against).

As a handful of prominent Republicans announce their support for gay marriage, some voters find a way to accept that change.

"There's a fair amount of evidence,” Crowder-Meyer says, that “when your party elites shift their opinions on an issue, the partisan voters and the electorate sort of follow the elites.” These folks opt to change their views rather than change parties.

Davis points out that as more Americans are comfortable identifying as LGBT, a growing number of politicians will find themselves with relatives or neighbors who are openly gay—and perhaps married.

"That's where you begin to see some heartfelt change in people," Davis says. "It's driven by personal circumstance. It's not political.”

Davis was surprised that that wasn't a factor in Liz Cheney's approach and wonders if it might have been personally and politically more effective for her to support her sister’s choice publicly.

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